1. Field of the Invention
This invention relates to an optical transceiver, which has an optical subassembly (herein called OSA) accommodated in a chassis, that can enhance accuracy for positioning the OSA.
2. Description of the Related Art
Optical transceivers comprise an OSA equipped with a built-in optical element for optical transmission/reception, accommodated in a chassis. In detail, the OSA comprises an optical module with optical elements accommodated in a package together with lenses and lead wires for electrical signals, and a cylindrical receptacle attached to be integral with the optical module. The optical transceiver is constructed such that the OSA is accommodated and fixed in the chassis with an entrance for an optical fiber formed therein. A position where to place the OSA is important because it influences quality of optical coupling between an optical path and the optical fiber. Although the position includes a position in a longitudinal direction of the optical path and a position in an orthogonal direction to the optical path, the position in the longitudinal direction of the optical path will mainly be described below.
To place the OSA at a proper position in the chassis, an OSA holder is used. The OSA holder engages a receptacle to hold the OSA, and is accommodated in contact with an inside portion of the chassis. Specifically, the OSA holder contacts a proper inside portion of the chassis so that its position is regulated and thereby determined in the chassis, while the receptacle is held by the OSA holder so that its position relative to the chassis is determined (see JP-A-2004-103743).
In the optical coupling between an optical path from the optical element and an optical fiber, of factors of positional mismatch in the longitudinal direction of the optical path, as the factors resulting from an optical transceiver, there are errors such as positional error of OSA fitting relative to a chassis, dimensional error (also called dimensional tolerance) of an OSA holder itself, positional error of OSA holding relative to an OSA holder, dimensional error of an OSA itself, etc. The more the number of parts involved in position determining, the more the dimensional and relative positional errors of the parts increase.
The discrete errors of the optical transceiver are 0.1 mm or less. However, the plural error factors combine together to cause an increase in total error, and therefore large positional mismatch unfavorable to optical coupling.